Process of producing cellulose acetate yarns and product thereof



Patented Oct. 10, 1933 V UNITED STATES PATENT PROCESS OF PRODUCING CELLULOSE ACETATE YARNS AND PRODUCT THERE- Camille Dreyfus, New York, N. Y., and William Whitehead, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Original application April 21, 1928,

Serial No. 271,973. Divided and this application August 13, 1929. Serial No. 385,687

This invention relates to the preparation of yarns or films containing cellulose acetate from solutions containing the same.

This application is a division of our prior application No. 271,973 filed April 21, 1928.

An object of our invention is to prepare yarns from cellulose acetate, which yarns do not deluster, or which at least display a great resistance to delustering, when exposed to boiling Water, boiling aqueous soap solutions, or other delustering agencies that are apt to cause delustering of previously known cellulose acetate yarns.

A further object of our invention is to prepare yarns from acetone soluble cellulose acetate, which yarns will not become delustered, or which will become delustered but little, when exposed to boiling water, wet steam or other delustering agencies.

A further object of our invention is to use an alcohol, and particularly ethyl alcohol in the solvent mixture used in the solution of cellulose acetate employed in the spinning of yarns. Other objects of our invention will appear from the following detailed description.

Yarns or fabrics produced from acetone soluble cellulose acetate, or other cellulose acetates, when prepared in accordance with prior processes, lose their luster and become opaque when treated with hot or boiling water. This delustering action is accentuated by the presence of soap or certain salts. Therefore, in the dyeing or washing of such yarns or fabrics, care must be taken that the temperature of the dyeing or washing bath be not too high, else delustering may result.

We have discovered the surprising fact that if a cellulose acetate, and particularly an acetone soluble cellulose acetate, is spun from a solution containing a solvent for the cellulose acetate and an alcohol, particularly ethyl alcohol, in small proportions, the yarns produced thereby display a resistance to delustering. The resistance to delustering of the yarns increases with progressive decrease of proportions of alcohol used in the case where smaller percentages of alcohol are used.

In accordance with our invention, yarns or films are made from a cellulose acetate, and particularly from a cellulose acetate that tends to deluster as set forth above, when spun in the old manner. The cellulose acetate is dissolved in a solvent mixture containing alcohol, preferably in very small amounts, and the solution thus formed is spun.

proportion of ethyl alcohol to the acetone used the use of acetone as a solvent gives excellent results. The diluent used may be any suitable alcohol, but we prefer to use ethyl alcohol, and

because of commercial expediency, it is advisable to use denatured alcohol of 95% strength, and this invention will, therefore, be more specifically described with respect to the use of such denatured alcohol as the diluent.

The ratio of the acetone to alcohol used in the solution may be varied within limits. Thus we have found that in those cases where the is small, that is, less than 5% of the solvent mixfture, the less alcohol used the greater the resistance to delustering. As stated before, the solutions may be spun by a wet or a dry spinning method. However, we prefer to employ a dry spinning method. In dry spinning, the temperature of the spinning should be varied to take care of the dilference of the volatility of the solvent mixture; i. e. the greater percentageof ethyl alcohol used the higher the temperature required. Thus, for chemically pure acetone, a

temperature of 50 to 55 C. may be used, while for a mixture containing acetone and 5% ethyl alcohol, a somewhat higher temperature may be used with advantage.

The yarns produced by the above described method, when boiled in water or water containing soap or other alkaline material, or when exposed to wet steam, show a greatly increased resistance to delustering as compared with yarns 95 made from cellulose acetate in accordance with prior processes.

In order to further illustrate our invention, the following specific example is given, but it is to be understood that our invention is not limited to the details set forth therein.

Example We take a cellulose acetate having an acetyl value of 54.5% and a'viscosity of 20 (as determined on an Ostwald Viscosimeter with a solu tion of 6 grams of cellulose acetate and 100 grams of acetone, the viscosity of glycerine being called 100). This cellulose acetate may be placed in a vacuum drier if desired, where it is dried at an elevated temperature under a vacuum of 25" of mercury (i. e. 5 of mercury absolute pressure), until its moisture content is reduced below 1%. However, the use of a cellulose acetate having a normal moisture content of 5% is not excluded. The cellulose acetate is then dissolved in a mixture containing 95% or more of acetone and 5% or less of denatured alcohol to form a solution containing substantially 25% cellulose acetate. The denatured alcohol preferably contains 95% by volume of ethyl alcohol and 5% of water and denaturant. The solution is then filtered and spun in a dry spinning machine wherein the solvent is evaporated off at a temperature of to C. or higher, the thread thus formed being gathered up and wound or reeled. The yarn produced in this manner shows a remarkable resistance to delustering, thus, while yarn prepared in the old manner becomes almost completely delustered or crinkled and opaque when boiled in water for a period of 15 minutes, the yarn made in accordance with ,this example is not delustered at all or only slightly so, and its opacity is but slightly affected after boiling minutes in water. Even boiling in a 0.5% soap solution hardly affects the luster or opacity of the yarn prepared in accordance with this example.

The process of this invention maybe applied to the obtaining of many beautiful effects in woven or knitted fabrics. For instance, a yarn may be woven, of which the warp consists of yarn spun from a charge dissolved in a solvent mixture containing 95% or more of acetone and 5% or less of ethyl alcohol, while the weft may consist of a yarn spun in the old manner. This fabric may be boiled, either by separate treatment or in scouring, dyeing or finishing, with the result that the warp, which is highly resistant to delustering, is hardly affected in appearance, while the weft becomes pronouncedly delustered and opaque, thus producing a fabric which is lustrous on one side and which has a dull matte appearance on the other.

By way of further illustration, it 'is pointed out that the lustrous figures or designs against dull backgrounds or vice versa may be obtained by weaving the two kinds of yarns by well known mechanical expedients of weaving and by subsequently boiling or steaming.

While this invention has been described specifically with respect to the use of cellulose acetate, it may also be applied to such cellulose esters such as cellulose formate, cellulose acetate or cellulose propionate which possess the same properties as the cellulose acetate described above. It is to be understood that the expression solvents of certain concentrations as used in the appended claims include solvents or solvent mixtures of certain concentration or degree of admixture.

It is to be understood that the foregoing details are given merely by way of illustration, and that many variations may be made therein without departing from the spirit of this invention.

Having described our invention, what we claim and desire to secure by Letters Patent is:

1. The process of producing articles comprising shaping a solution of an organic ester of cellulose in a volatile solvent mixture containing a solvent therefor and alcohol, wherein the alcohol present comprises no more than 5% of the solvent mixture, and then causing the volatile solvent to evaporate.

2. The process of producing articles comprising shaping a solution of cellulose acetate in a volatile solvent mixture containing a solvent therefor and alcohol, wherein the alcohol present comprises no more than 5% of the solvent mixture, and then causing the volatile solvent to evaporate.

3. Method of producing yarns that are resistant to the delustering action of, boiling water from acetone soluble cellulose acetate, comprising dissolving such cellulose acetate in a mixture containing a solvent therefor and no more than 5% of alcohol and then dry spinning the resultant solution.

no less. than 95% of acetone and no more than 5% of ethyl alcohol and then dry spinning the 

